Tahoe vibrating at idling while in Drive

I am hoping someone can help... I have a ’01 Tahoe and it has started to vibrate heavily while I am in Drive and stopped at either at a stop light or in traffic. I have cleaned the intake manifold and even switched to a high octane gas. However the vibration will not go way, it seems to only lessen. Any suggestions? Thanks everyone.

It sounds like it is misfiring. Any more symptoms?